Fears of an imminent major eruption of Bali's Mount Agung have increased and the evacuation zone around the volcano has been widened.
Indonesian authorities have raised the state of alert to its highest level.
The island's airport has now closed, leaving thousands stranded in the tourist hotspot.
Authorities say dark smoke and ash have been billowing up to 3,400m (11,150ft) above the mountain's summit, which has also been emitting fire.
Officials have warned residents to stay away from rock and debris flows known as lahars, which have been spotted flowing down from the mountain.
The National Board for Disaster Management raised the alert to level four from 06:00 local time (22:00 GMT Sunday), because of "the possibility and imminent risk of disaster".
The volcano was seen emitting "continuous ash puffs" occasionally accompanied by "explosive eruptions" and "weak booms" that could be heard 12km (7 miles) from the summit.
"The rays of fire are increasingly observed at night. This indicates the potential for a larger eruption is imminent," it said in a statement (in Indonesian) on its Facebook page.
Geologist Mark Tingay of the University of Adelaide told the BBC that Mount Agung now appears to be entering the next phase with a magmatic eruption, where the glow of lava is visible from the crater.
But he added that as eruptions are difficult to predict, it was "very hard to tell" how the situation would develop. "These eruptions can be quite large and extensive and violent, but this could also be a relatively minor eruption over time".
He added that Indonesian authorities had made preparations for an eruption for months, and said they appeared "extremely well prepared" with the situation "well under control".